A number of dispensing devices are available for dispensing various types of materials. In many instances, the dispensing device is an assembly that includes a reusable dispenser or applicator and a disposable cartridge. The cartridge typically comprises one or more compartments. Container, such as foil bags, containing the material to be dispensed are accommodated in the compartments of the cartridge. The cartridge contains a quantity of a material to be dispensed and is releaseably received in a receptacle or chamber of the applicator.
In one type of dispensing devices, that include an applicator and a cartridge, the applicator has a plunger that is advanced by the user during a dispensing operation. Often, the plunger is positioned at an open end of the cartridge and bears against a piston within the cartridge. As the plunger is advanced to move the piston, the piston expels a quantity of material through a front outlet opening of the cartridge, where it may be mixed with material expelled from another cartridge, or used by itself. Dispensing devices with cartridges are often used in the field of dentistry for mixing and dispensing dental compositions of two components, such as impression materials, restoratives, adhesives, cements, etching gels, sealants and the like. The dispensing cartridge of such devices is made from a plastic material and comprises two compartments formed by two cylindrical bodies arranged in parallel to each other. Each compartment contains a specific component, usually a base paste or a catalyst paste, each contained within its own container, such as a foil or plastic bag. These two components are pressed from their respective foil bags out into a mixing tip where the required dental material is prepared. The pressure further urges the mixture out of the mixing tip so that the dental professional can use it as desired.
One type of such dispensing devices is an assembly (e.g., the Garant™ dispenser available from 3M ESPE AG) that includes a reusable, hand-operated applicator and a disposable cartridge (e.g., the cartridge for the polyether impression material Permadyne™ Garant™ available from 3M ESPE AG). The two compartments are of the same cylindrical shape and size and are pre-filled with the two components to be mixed and dispensed.
Another type of such dispensing devices is an automatic dispensing system (e.g., Pentamix™ available from 3M ESPE AG) that includes a motor-driven mixing or applicator unit and reusable and interchangeable cartridges (e.g., the cartridge for the polyether impression material Impregum™ Penta™ H DuoSoft, or the cartridge for the polyether impression material Permadyne™ Penta™, or the cartridge for the vinyl polysiloxane impression material Express™ Penta™ H, all available from 3M ESPE AG). The applicator unit comprises a space that receives the cartridge, and a cover that closes the space once the cartridge is placed in the dispensing device. The two cylindrical compartments of the cartridge have different diameters, and, in use, each accommodates a disposable foil bag pre-filled with the respective component. The larger compartment accommodates the foil bag with the base paste. The smaller compartment accommodates the foil bag with the catalyst paste. The mixing or applicator unit comprises a chamber for holding the cartridge and two parallel motor-driven plungers designed to plunge into the respective compartments and to exert pressure on the components contained in the foil bags. Both foil bags comprise a respective cap that fits onto the rim of the respective cylindrical body of the dispensing cartridge. A pivotable lever is used for locking the mixing tip so that it does not fall off of the caps of the foil bags when pressure is applied by the plungers.
FIG. 1 shows such a conventional cartridge 1 having two parallel cylindrical compartments 2, 3 with different diameters. In FIG. 1, each compartment already accommodates a foil bag comprising respective caps 4, 5. Each cap comprises an outlet tube (in FIG. 1, only the outlet tube 6 of cap 4 is shown), and adjacent to these outlet tubes is a mixing tip 7. A lever 8 that extends along the longitudinal axis of the cartridge is pivotally hinged to the cartridge at its rear end. At the front end of the lever 8, the lever comprises an essentially U-shaped locking member 9, comprising two locking arms that engage corresponding locking surfaces or flanges of the mixing tip 7. This positions the mixing tip properly relative to the outlet tubes 6 of the caps.
FIG. 2 shows the cartridge 1 with the lever 8 in its fully engaged position. Due to the two locking arms engaging a circumferential flange at the rear end of the mixing tip 7, the mixing tip 7 is held tight against the outlet tubes 6 of the foil bag caps 4, 5. In order to hold the lever 8 in its engaged state, an engagement mechanism 10 is provided which engages a corresponding surface at the underside of the lever 8. This engagement mechanism 10 can be released by means of a release slide 11. In order to facilitate a quick release of the lever 8 from mixing tip 7, a leaf spring 12 is provided adjacent to the lever hinge 13. Once the engagement mechanism 10 is released with the release slide 11, lever 8 springs upwards and away from the mixing tip 7 due to the bias force of the leaf spring 12.
FIGS. 1 and 2 also show a handle 14 that is provided at one side of the cartridge, specifically on the side of the larger diameter compartment 3. With this handle 14, the cartridge 1 can be picked up and removed from the applicator unit, for example, so that the foil bags can easily be changed. However, since the handle 14 is provided at a side of the cartridge 1 like a wing, removal of the entire cartridge 1 from the mixing unit might be inconvenient to the user.
EP 1 044 727 A2 relates to a device for mixing and dispensing of a viscous liquid consisting of at least two components via two pistons. The liquid components are held in containers that are part of an insert and connected to a mixer. The pistons are arranged in a housing of the device and act upon such containers. The insert is accommodated in a cartridge that is part of a housing attachment. The cartridge is rotatably connected with the housing attachment so that it is rotatable between an operating position and an open position, wherein the insert can be removed from or inserted into the cartridge in the open position, and the insert can be secured in the cartridge in the operating position.
U.S. Pat. No. 5,184,757 generally relates to gun-type dispensers for discharging a viscous fluid or paste, such as a sealing or bonding agent, from a container storing this agent. The gun includes a pair of cylindrical barrels for accommodating sealed foil packs having stored therein two components to be extruded and intermixed. Fitting into the leading ends of barrels and are end caps and of a mixing manifold. The manifold, which is removable from the barrel, is locked in place by a swing gate having a pair of parallel arms whose rear ends are pivotally connected to opposite sides of a stock piece. Secured to the front ends of these arms is a gate which when the gate is lowered engages the exposed faces of caps. When the swing gate is thereafter raised, one may then withdraw the manifold from the barrels.
U.S. Pat. No. 2,634,888 relates to a dispensing gun with means for inserting removable containers. The apparatus described in U.S. Pat. No. 2,634,888 comprises essentially a handle carrying a manual mechanism for expelling the contents the cartridge and having means for positioning the rear end of the cartridge; a cup-like member to engage the front end of the cartridge and an extensible connecting device between said front engager and the handle whereby the cartridge may be effectively clamped in the apparatus to constitute the barrel of the gun or be released therefrom when empty. The clamping mechanism comprises a pair of frame bars extending parallel with each other on opposite sides of the cartridge, and have sliding or telescoping engagement with a pair of side bars which are secured to the front abutment. An operating lever is pivotably linked to the frame bars, and the operating lever and suitable linkage connects with the bars in a manner to spread them or contract them. With such arrangement, which is shown in FIG. 2 of U.S. Pat. No. 2,634,888 for example, a pivotal or rotational movement of the operating lever is translated into a translational movement of the frame bars and side bars relative to each other in order to clamp the cartridge in the apparatus.
EP-A-1 602 342 (document under Art. 54(3) EPC) relates to a dispensing cartridge having a locking assembly for locking a tip in position relative to at least one compartment. The locking assembly comprises a first movable member comprising a first end and a second movable member comprising a first end and a second end. The second end of the second movable member is adapted for releasable locking engagement with the tip. The first movable member is operationally connected to the second movable member such that a movement of the first end of the first movable member is transmitted to the first end of the second movable member causing the second movable member to also move. Movement of the first end of the first movable member in a first direction causes the second end of the second movable member to release the tip, and movement of the first end of the first movable member in a second direction causes the second end of the second movable member to engage the tip. The first movable member may form part of a handle.
Further reference is made to EP-A-0 291 753, EP-A-0 910 995, WO 97/18145, DE-A-100 38 882, and DE-A-34 18 052.